iOS Unable to Check for Update- Deferment issue?

[Gern]

We have iOS updates restricted to 30 days from release to hopefully work out kinks was the thinking. Our entire fleet was on 11.3.1 a handful of students upgraded themselves to 11.4.1 which was all good. We have had some charging issues and apple wants us to upgrade all to 11.4.1. Doing my small tests before sending it out globally I am running into about half not able to auto download and install. When I grab the devices there is already a red 1 next to general but when I click on Software Update it says Unable to Check for Update and are stuck on 11.3.1. Do I have to get rid of Software deferment? Anyone have any leads to check into?

[bfrench]

We are seeing a similar issue. Once the 30 days had passed on iOS 12 we had students able to upgrade. This week devices that are on 11.4.1 - when they try to update- receive the message Unable to Check for Update.

[cbrewer]

There's an issue where, if the deferred update available is 12.0.1, the update check fails. Apple is aware and supposedly a fix is coming soon. The short-term fix is turn off deferred updates and let them go to 12.1.

[andrewmac]

If a device is more than one update behind the latest, and have deferred updates installed, can you install and verify the second-to-latest iOS version or update?

(e.g. Device has 11.4.1 today, deferred updates configured for 90 days, cannot verify 12.1.1 update because 12.2 is out, but is still in 90 day deferred period.)

@cbrewer Is this the issue Apple is aware of?